# CVE-2026-87933: DaveGamble cJSON cJSON_Utils.c cJSONUtils_MergePatch use after free

> A use-after-free vulnerability in cJSON's MergePatch function allows remote attackers to potentially execute code or cause denial of service.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Sep 2026
- **Updated:** 10 Sep 2026
- **Also known as:** AZL-100911, DEBIAN-CVE-2026-87933, ECHO-bdd3-ee8d-c65f, GHSA-7jcg-95pj-h5fp, UBUNTU-CVE-2026-87933

## What is CVE-2026-87933?

CVE-2026-87933 is a medium-severity use after free vulnerability in DaveGamble cJSON, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was found in DaveGamble cJSON up to 1.7.19. The affected element is the function cJSONUtils_MergePatch of the file cJSON_Utils.c. The manipulation results in use after free. The attack may be launched remotely. The exploit has been made public and could be used. The pull request to fix this issue awaits acceptance.

Weakness: CWE-416 (Use After Free), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-87933?


## How do I fix CVE-2026-87933?

Apply the vendor's patch.

## Is CVE-2026-87933 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87933 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87933 and fix it if it is affected.

What it is: CVE-2026-87933 is a medium-severity use after free vulnerability in DaveGamble cJSON, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87933 exists.

Affected product: DaveGamble cJSON. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-87933/ (Markdown: https://insights.sbomify.com/CVE-2026-87933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87933
- OSV: https://osv.dev/vulnerability/CVE-2026-87933

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-87933/
Summaries are generated and may contain mistakes; the official description above is the record.